US Patent 7334392 Counter-rotating gas turbine engine and method of assembling same

A method for assembling a gas turbine engine includes providing a first fan assembly including a plurality of rotor blades that are configured to rotate in a first rotational direction at a first rotational speed, rotatably coupling a second fan assembly axially aft of the first fan assembly, wherein the second fan assembly includes a plurality of rotor blades that are configured to rotate in a second rotational direction, and coupling a gearbox to the second fan assembly that is configured to rotate the second fan assembly at a second rotational speed that is different than the first rotational speed.